Heater coil



April 8; 1930. c, c, c fT 4 1,753,296

HEATER COIL Filed March 10, 1926 w ,6 l in l 7 Patented Apr. 8, 1930 PATENT omen CHARLES C. MGDERMOTT, OF CHICAGO, ILLINOIS HEATER 0011.

Application filed March 10, 1926. Serial No. 93,776.

This invention relates to animproved heater coil, particularly adapted for submerged heaters, and the like, and more particularly the invention relates to an improved tube, head, and connection construction, and provides an improved process of securing the tube in the head and connection of such structures.

V In the construction of heaters of this type,

it it is particularly desirable that the joints between the parts of the coils be made as nearly homogeneous as possible, and that the joints be strong and tight.

At present these tubes and the associated 1 head and connecting members are commonly joined by welding or brazing. These connections are more difficult and moreexpensive to make than the connections whichmy present invention provides, and they are notentirely satisfactory in use. I A

It is the object of my invention to pro; vide an improved and simplified method of connecting these parts, and an improvedcoil construction that will better serve the purposes for which intended than the coil constructions heretofore provided-.-

According to my presentinvention, I make the head, connecting,-or other members, of an alloyed metal having a lower melting point than the tubes, and I castthe head members and connections directly upon the tube or tubes as an insert. Although other metals or alloys having the desired relative melting points may, of course, be employed, the tubes are preferably of copper and" the head members and connections are preferably of yellow brass.

Where the melting point of the head member and connection is considerably lower than that of the tubes, red metal, or the like, may be addedfor the'purpose of raising the melting point of the head and connection up to a point near that of the tube,'preferably to a point so that the tubebeg'ins to soften or even flow j-ust'slightly as the head a'nd'connection is cast thereon. By red metal, which is referred to in non-ferrous foundry practice, I refer to a brass alloy having more copper or a high copper content. The copper makes it red and a'mixture high in copper melts at an increasingly high temperature as the copper is added. The tube and other parts are thereby united into practically a single unitary homogeneous structure, and the internal stresses of welding or brazing are avoided.

Ialso provide an adjustable mounting for the coil which will be universal in its application to different boiler plates and supports. This mounting permits ready accommodation to variations in such supports.

To acquaint those'skilled in the art with the manner of constructing and practicing the invention, I shall now describe the same in connection with a particular embodiment of the invention.

In the drawings v Figure 1 is a front elevational view of a heater coil embodying the invention;

Fig. 2 is a vertical longitudinal section axially through the inlet to and outlet from the head of the coil-and ofiset to extend aX- ially through the tubes thereof; and

Fig. 3 is a top plan view partially in section of the'head of the coil and the adjacent ends of the tubes as viewed in Fig. 1.-

While the present invention is not limited thereto, .it has particular utility in connec tion therewith and, therefore, where I refer toa submerged heater I mean those heaters which are disposed in the boiler below the water level'thereof and usually above the usual heating tubes of the boiler. This-is all well understood in the'art and I will, there gore, omit any further details of the same ere.

The heater section shown comprises a plurality of circulating tubes 5, 5 and 6, 6 joined at their frontends to a head 7 and connected at their rear ends by a connecting box or connector 8. 1

The head? is coredto provide an inlet chamber 10 and an outlet chamber v1 2. The tubes 5, 5 open from the chamberl'O and the tubes 6,6 open into the chamber 12; The employment of the tubes 5 and 6 in pairs is simply for capacity and one or any number of tubes may be employed in this connection. The inlet chamber 10 be connected by means of a suitable conduit 14: with the bottom of the water tank (not shown), for ex ample, and the outlet chamber 12 may be connected as by means of the conduit 15 with the top, for example, of the water tank.

The chambers 10 and 12 may be separated by a partition 18 having a suitable vent opening 20 for venting air and permitting circulation through the coil, which is usually a gravity circulation in heaters of the submerged type. hen the outlet leg becomes lighter than the inlet leg to the heater coil, the difference causes the gravity circulation through the coil, as well understood in the art. The coil may be supported at only the I front or head end and the vent 20 will vent any air in the case of sagging of the rear end, and thereby permit proper circulation through the coil at all times.

The tubes 5 and 6 are preferably of copper, although this may be varied, as will be pointed out, and in making up the coil the head ends of these tubes are laid and suitably supported in the mold for the head member 7. The head member 7 is preferably formed of yellow brass, although this may also be varied, and with the adjacent ends of the tubes 5 and 6 inserted as inserts in the mold for the head member 7, the molten brass is poured into the mold and upon and around the tubes 5 and 6.

The melting point of the copper tubes is in the neighborhood of 1950 F. and the melting point of the brass forming the head is in the neighborhood of 1350 F. The particular relation of these melting points may vary as will, of course, occur where different alloys or other materials are employed in carrying out my invention.

Where the alloys and melting points above pointed out are employed, which are merely illustrative, it may be desirable to add red metal, or the like, to the brass, for the purpose of raising the melting point thereof up to a point near that'of the melting point of the copper tubes. Where the relative melting points are such that the melting point of the material employed for the head nearly approaches that of the material employed in the tubes, the addition of red metal, or the like, for the purpose of raising the melting point of the head material is, of course, unnecessary.

By providing an alloy for the head, the melting point of which nearly approaches that of the metal or alloy in the tubes, the

\ adjacent ends of the tubes will in the pouring and casting of the head soften or even nearly approach the point of flowing, so that as the head-sets or hardens it and the adjacent ends of the tubes will in eflect run together and provide in effect an integral homogeneous tube and head structure. Then, when the head part hardens completely, it and the tubes are removed from the mold and form, in effect, an integral unit with the connections between them strong and tight and without any internal stresses such as are commonly introduced in welding or brazing the parts together. The resulting structure is simpler and less expensive to make, from the standpoint of construction or joining these parts, and it is better adapted for the purposes for which intended.

The connection or box 8 at the opposite or rear ends of the tubes 5 and 6 may be of the same material as the head 7 and it is preferably cast upon the opposite ends of the tubes 5 and 6 in substantially the same manner. The box or connection 8 simply connects the opposite ends of the tubes 5 and 6, and the water or other fluid flows from the tubes 5 through it and to and out through the tubes 6.

The open end of the connection or box 8 may be closed by a suitable cover which may be suitably secured in place thereover. This cover 30 may be made removable for cleaning purposes or it may constitute an integral part of the connecting member 8.

The use of an alloy or material in the head members having a lower melting point than the material of the tubes, and the manner of utilizing these melting points to pour the molten head material and cast it upon the tubes without melting the tubes, but at the same time softening them sufficiently to pro vide a homogeneous union between the tubes and head, are highly important aspects of my invention. As already pointed out, the particular materials employed to this end maybe widely varied, but for example, a cast iron head with a much higher melting point could not be oined to a copper tube in this manner. At the same time the tubes 5 and 6 may be of an alloy or material other than copper, so long as the melting point of the head material is lower or at least is lowered below that of the melting point of the tubes.

In use, the inner ends of the tubes 5 and 6 with their connection 8 are inserted through the opening in the boiler plate 38, and the head 7 is then bolted or otherwise suitably fastened to the plate 38 with a suitable gasket 40 therebetween. The gasket 40 may conveniently be a softer material such as lead.

Molded or cast integrally, for example, with the opposite sides of the head member 7 and extending laterally therefrom are a pair of mounting flanges and 52. Each of the flanges 50 and 52 has two elongated, generally arcuate apertures or openings 53, 53 and 54, 54, respectively. These flanges 50 and 52 with their arcuate, elongated openings 53 and 54 provide an adapter mounting for the coil and permit mounting of the coil upon different boiler plates and different other supports. Furthermore, this universally adapts the coil for different arrangements of mounting bolts and for different arrangements of bolt openings and for the structural variations which are bound to occur in plates and supports of the same type.

I find that by employing one bolt 60 in the lower aperture or opening in one flange and a second bolt 62 in the upper opening of the other flange, a strong mounting is provided which is self aligning and which is balanced, one side against the other, so that the coil can not accidentally turn about its mounting. In fact, I find that by providing a suitable pocket therefor centrally of the head 7, and sealing the plate against leakage about the pocket and mounting bolt, a single central mounting bolt may be admirably employed for firmly fastening the entire coil to the boiler plate or other support.

Whereas I refer to connecting the conduit or tube 14 with the bottom of the water tank' and the conduit 15 with the to of the water tank, these connections and t e system in which the coil or tube of my'invention is used, may be widely varied.

For example, it is impossible to place a long heater tube or coil of this sort in some boilers and a shell is placed along the outer side of the boiler with the heater in this shell. The coil or tube of my present invention is also admirably adapted for this use, in which the boiler water is usually circulated through the heater coil from just below the water level in the boiler and returns through a connecas an insert in the mold for the head member,

melting the material of the head member at a temperature below but near the melting temperature of the material of the tube, pouring the molten head member material into the mold and directly upon the inserted part of the tube and casting the head member directly upon the tube to produce a substantially integral and substantially homogeneous joint between the head member and the tube without distorting the interior of the tube.

In witness whereof, I hereunto subscribe my name this 6th day of March, 1926.

CHARLES C. MCDERMOTT. 

